SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b51100b0ae986d7ef7be4535dc552d93182dff0321fbb8e739943b42a7c2dba' 
  AND token = 'QYlLessVUYrwzUjEPshJsjC/3nsPP7m3MoKdxvrmlDg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}